As Dam-IT has some effects on reducing seepage flow, therefore it is satisfactory to remediate earthen dam. The result ranges in broad spectrum because applying Dam-IT depends on sample soil layer and its mechanism in different inclined planes on upstream slope.
Tuyển tập Hội nghị Khoa học thường niên năm 2018 ISBN: 978-604-82-2548-3 THE POSSIBILITY OF APPLICATION DAM-IT MATERIAL TO REMEDIATE SEEPAGE ISSUES FOR SMALL AND MEDIUM RESERVOIRS IN VIETNAM 2 Nguyen Ha Phuong , Ho Sy Tam , Nguyen Phuong Dung Institute of Civil Engineering, email: nguyenhaphuong@tlu.edu.vn Hydraulic Division - Thuyloi University relief drains can be installed to relieve water pressure In this research, DAM-IT material was studied its ability to limit – without cease – As reported by Directorate of Water seepage flow by applying in upstream face of Resources (2012), there are about 6886 dams embankment dam For small and medium in Vietnam, in which over 90% is earthen reservoirs [2] it is essential to promptly handle dam [1] – nearly 1200/6886 needs to seepage issues while ensuring rational total remediate without delay Although, these investment – DAM-IT material could meet earthen dams have been played an important these requirements Technical characteristics of role in ensuring water resource security, they DAM-IT material are discussed below also have been revealed many risks for the downstream due to dam safety issues, INTRODUCTION AND MECHANISM especially the seepage problems OF DAM-IT MATERIAL Seepage is the continuous movement of In order to withstand with the challenge of water from the upstream face of the dam toward its downstream face Seepage can climate change as well as other random emerge anywhere on the downstream face, events and to ensure the safety of people's beyond the toe Its appearances could range lives and downstream property, solving from a "soft" wet area to a flowing "spring" It safety problem and handling of dam incidents may show up first as an area where the are extremely urgent Due to the time limit vegetation is lush and darker green Seepage for research, this research is mainly focusing can also saturate and weaken portions of the on the seepage issues of the dam and the embankment and foundation, making the ability of applying Dam-IT material in the embankment susceptible to earth slides If the conditions of Vietnam Dam sealer is a new seepage forces are large enough, soil could be and very effective material in reducing the eroded from the foundation and be deposited in leak volume and hence diminishing the seepage forces in dam’s body, consequently the shape of a cone around the outlet The need for seepage control will depend increasing the safety of the dam on the quantity, content, and location of the Figure seepage If the seepage has lowered the The material reservoir water level or endanger the dam or expanded its appurtenant structures, it is time to take size and action over seepage issues although reducing the quantity of seepage that occurs after floated in the construction is difficult and expensive water Typical methods used to control the quantity of seepage are grouting or installation of an Shalex indus tries is a specialist manufacturer upstream blanket; in addition weep holes and of clear sealers and waterproofing compounds APPROACH TO SEEPAGE ISSUES FOR SMALL AND MEDIUM RESERVOIRS 595 Tuyển tập Hội nghị Khoa học thường niên năm 2017 ISBN: 978-604-82-2548-3 that include Dam-IT (or Dam sealer) material to prevent seepage for dams and ponds [3] The Dam Sealer was applied in physical models to evaluate the total reduction volume and from this point of view the effectiveness of Dam Sealer was estimated Dam-IT is designed with a pos itive charge that pulls it down under the water toward the bottom of the dam or pond with upstream slope m1 =2 and downstream slope m2 =1,8 The water column at upstream site was 0,4m compared with the foundation of the dam; the tail water level was controlled at 0,08m The upstream head was refilled to reach the value of 0,4m after 24 hours Behind the mica plate was a collecting part to measure the seepage volume to the downstream site The design dam model was illustrated in figure and figure Figure Dimension of the model Figure Physical model The water pres sure (hydrostatic pressure), which causes the dam or pond to leak, forces the polymer down into cracks and crevices as it sinks to the bottom of the pond or dam Once activated with water, the polymer will expand in size and bind to other polymer particles to form larger groups of particles, which effectively slows and stops the leak The polymer will continue to expand over s everal hours and forms a flexible plug that withstands water pres sure The positive charge of the particles will also attract any silt and sus pended matter in the water downward to the bottom, which acts to embed the polymer within the soil structure and minimize any disturbance or movement of the polymer that may be caused by future water inflows By attracting the small particle and soil particle in the water body, Dam Sealer creates a new cover layer on the top of upstream surface and then reduce the seepage volume PHYSICAL MODEL AND RESULTS The model was compacted using soil sample with identified mechanical properties as following: W op t based on TCVN 4201:2012 (W op t =14,52% and γ=1,89g/cm3, respectively); =31,25o, C=7,95 kN/m2 based on TCVN 4199 : 1995; and K= 6,04e-6 cm/s based on TCVN 8723 : 2012 After constructing physical model and filling water, seepage volume was measured until it reached stable There were cases to carry out experiment: before using Dam-IT material (table 1) and after applying it (table 2), each case was operated in weeks The Dam-IT was mixed with soil sample in order to increase its efficiency and accelerate the settle speed In the research, the ratio 3% was chosen (30g Dam Sealer/ 1000g soil sample) The time between each measurement period was 24h, 18h, 12h Table Diary recording before applying the material Time UH* DH** Dam(cm) (cm) age 3p.m (9/2)33 3p.m(10/2) 3h30p.m(10/2)- 35 3h30p.m(11/2) 4p.m(11/2)33,5 4p.m(12/2) 4h30p.m(13/2)- 34 4h30p.m(14/2) 5p.m(14/2)33 5p.m(15/2) Average Q(m3/s) 27 3,13E-07 28,5 6,5 3,30E-07 27,5 3,18E-07 27 3,13E-07 27,5 5,5 3,18E-07 3,18E-07 The total height of the model was 1,1m with UH* - Upstream hydraulic Head; DH** 0,1m for the foundation made of mortal and 1m heigh for retaining water and soil The total Downstream hydraulic Head The particular picture used for illustrating length was 2,5m and the designed width was 0,8m The height of the dam model was 0,5m the water level at upstream site and 596 Tuyển tập Hội nghị Khoa học thường niên năm 2018 ISBN: 978-604-82-2548-3 downstream site in a particular day because CONCLUSION the phreatic line was stable and the filling As Dam-IT has some effects on reducing volume of water didn’t change much in the seepage flow, therefore it is satisfactory to period of weeks remediate earthen dam The result ranges in broad spectrum because applying Dam-IT depends on sample soil layer and its mechanism in different inclined planes on upstream slope Since Dam-IT is a new and effective material, further research is needed so that user can deeply understand how to use this material efficiently Several properties and application should be known, such as the best ratio between soil and Figure The water level at upstream site Dam-IT material, the lifespan of the material after 24 hours of observation (10/2-11/2) and other methods of applying this material, the In the physical model, the Dam Sealer construction techniques for it and also the layer was settled down under the forces ability of applying it on larger scale The impact of Dam-IT on the environment exerted by the water, besides that the concentration of Dam Sealer material was also needs further research although from data of distributed non-uniformly, so this could Shalex company and in our research have reduce the effect of material Dam-IT could observed that it does not harm to the environment Another approach of research on this reduce seepage volume in physical model material is the optimal concentration of Dam after 2-day of application Sealer for reducing the seepage volume With Table Diary recording after applying the the dam model, the effectiveness of Dam DAMIT material Sealer is recommended as about 20% or higher When applying for the real dam, the UH DH Dama Time Q(m /s) turbidity of river can increase the efficiency (cm) (cm) ge like the mechanism that have been discussing 12p.m(22/2)7 5,5 1,5 2,55e-07 above For embankment dam in Viet Nam, its 6p.m(22/2) mechanism can be very effective on reducing 6h30p.m(22/2)24 17,5 6,5 2,70e-07 12h30p.m(23/2) the seepage volume in both dam body and foundation However, the method of 12h30p.m(23/2)- 27 21,5 5,5 2,59e-07 11h30a.m(24/2) applying still needs further research to identify the best construction and application 12hp.m(24/2)5 2,47e-07 4h30p.m(24/2) method of this material in Vietnam 5p.m(24/2)3p.m(25/2) Average 25.5 20 5,5 2,53e-07 REFERENCES 2,57e-07 [1] Report of Directorate of Water Resources, 2012 Values of discharge through dam’s body decreased more than 19,2% before and after [2] QCVN 04-05:2012 [3] https://www.shalex.com.au/damit-dam-sealer applying DAM-IT material (on average results [4] TCVN 4201:2012; TCVN 4199:1995; from table and table 2) It deserves the TCVN 8723:2012 effective of Dam Sealer on this physical model 597 ... water, the polymer will expand in size and bind to other polymer particles to form larger groups of particles, which effectively slows and stops the leak The polymer will continue to expand over... that include Dam-IT (or Dam sealer) material to prevent seepage for dams and ponds [3] The Dam Sealer was applied in physical models to evaluate the total reduction volume and from this point of. .. this material, the In the physical model, the Dam Sealer construction techniques for it and also the layer was settled down under the forces ability of applying it on larger scale The impact of Dam-IT